Pristine nanotubes are generally insoluble in common solvents and polymers. Such nanotubes are also difficult to chemically functionalize without altering the desirable intrinsic properties of nanotubes. Single-walled nanotubes (SWNTs) have been solubilized in organic solvents and water by polymer wrapping (Dalton et al., (J. Phys. Chem. B (2000) 104, 10012); Star et al. (Angew. Chem., Int. Ed. (2001) 40, 1721), and O'Connell et al. (Chem. Phys. Lett. (2001) 342, 265)), and noncovalently functionalized by adhesion of small molecules for protein immobilization (Chen et al., (J. Am. Chem. Soc. 123:3838 (2001))). The polymer wrapping approach works poorly for dissolution of small diameter SWNTs possibly due to unfavorable polymer conformations.
A process of noncovalent functionalization and solubilization of carbon nanotubes is described by Chen, J. et al. (J. Am. Chem. Soc., 124, 9034 (2002)) which process results in excellent nanotube dispersion using a nonwrapping approach. SWNTs were solubilized in chloroform with poly(phenyleneethynylene)s (PPE) along with vigorous shaking and/or short bath-sonication as described by Chen et al. (ibid) and in U.S. Patent Publication No. U.S. 2004/0034177 published Feb. 19, 2004, and U.S. patent application Ser. No. 10/318,730 filed Dec. 13, 2002; the contents of such patent applications are incorporated by reference herein in their entirety. The rigid backbone of a PPE cannot wrap around the SWNT in contrast to the polymer wrapping approach described above. The major interaction between the polymer backbone and the nanotube surface is described as parallel π-stacking. Thin film visible and near-infrared spectroscopy of PPE-solubilized nanomaterial demonstrated that the electronic structures are basically intact after solubilization. One such PPE-solubilized nanomaterial sample was obtained by filtration and redissolved in chloroform to a concentration of about 0.1 to 0.2 mg/mL (Chen et al. (ibid) and in U.S. Patent Publication No. U.S. 2004/0034177 published Feb. 19, 2004, and U.S. patent application Ser. No. 10/318,730 filed Dec. 13, 2002).
Further rigid polymers for solubilizing nanomaterials, compositions, and methods therefore are described herein.